Method and apparatus for mixing fluids

ABSTRACT

A gelatin medium is stirred in a three-chamber container which includes a rotating paddle turning at an adjustable constant speed in the lowest one of the chambers. Potassium halide and silver nitrate solutions are added to the other chambers at a constant velocity by an ejecting system driven at an adjustable constant velocity. The ejection system includes syringes which contain the above solutions and which dispense equal volumes of each solution per unit time into a gelatin medium in the container. The container is surrounded by a water jacket maintained at a constant temperature by a heating element controlled by an adjustable thermostat.

Elite tates tent [19] Buckingham et al.

[ Oct. 9, 1973 METHOD AND APPARATUS FOR MHXHNG F LUIDS [73] Assignee: international Business Machines Corporation, Armonk, N.Y.

[22] Filed: June 30, 1971 [21] Appl. No.: 158,310

[52] US. Cl. 259/24, 259/108 [51] Int. Cl. Bolt 7/18, BOlf 15/02 [58] Field of Search 259/7, 8, 23, 24,

Primary Examiner-John Petrakes Assistant Examiner-Philip R. Coe Attorney-Graham S. Jones, ll et al.

[57] ABSTRACT A gelatin medium is stirred in a three-chamber container which includes a rotating paddle turning at an adjustable constant speed in the lowest one of the chambers. Potassium halide and silver nitrate solutions are added to the other chambers at a constant velocity by an ejecting system driven at an adjustable constant velocity. The ejection system includes syringes which contain the above solutions and which dispense equal volumes of each solution per unit time into a gelatin medium in the container. The container is surrounded by a water jacket maintained at a constant tempera ture by a heating element controlled by an adjustable thermostat.

10 Claims, 7 Drawing Figures 0N OFF 52 PATENTED 91973 3.764.115

SHEET JJF 3 INVENTORS ROBERT L. BUCKINGHAM HAROLD H. HERD THERESA 1. SUN

ATTORNEY PAIENTED 9 73 SHEET 2 (If 3 PATENTEU [113T 9 I975 SHEET 30F 3 401F200 ammmm mOhOE 12.340 mom BACKGROUND OF THE INVENTION 1. Field of the Invention DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1-6 a mixing container is sur- This invention relates to mixing of different fluids 5 rounded at its base byawater jacket 11. The container and more particularly to mixing of constituents of a high resolution silver halide emulsion.

2. Description of the Prior Art Heretofore methods and apparatus for mixing constituents of silver halide photographic emulsions have produced a product with relatively larger particle size and greater variation and less uniformity in size than desired.

SUMMARY OF THE INVENTION An object of this invention is to provide an improved method and apparatus for mixing solutions to be combined chemically.

Another object of this invention is to provide a photographic emulsion having a desired uniform, small particle size.

In accordance with this invention a method and apparatus are provided for mixing two solutions with a medium, preferably gelatin, by mixing quantities of each solution separately with portions of the medium and then mixing the resultant mixtures.

Further, in accordance with this invention the medium is stirred continuously by a rotating paddle providing substantial turbulence of the medium and the mixtures.

Still further, in accordance with this invention, a container is provided including a chamber for containing the medium and stirring the medium. The container also includes separate chambers. Each chamber receives only one of the solutions to be added to the me dium. The separate chambers communicate with the first chamber and also include some of the medium and permit medium alone and with the solutions added to the medium to pass between the communicating chambers to provide a uniform dispersion of the contents of the solutions within the medium. Preferably, the rotating'paddle generates non-laminar or turbulent flow of medium and solution throughout all of the chambers as the result of very active agitation provided by the paddle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectional elevation of apparatus for preparing an emulsion by means of controlled stirring of a medium at a controlled temperature and for introduction of both chemicals in measured amounts at a uniform rate.

FIG. 2 is a downward view taken along line 2-2 in FIG. 1.

FIG. 3 is a sectional elevation of the container and water jacket shown in FIGS. 1 and 2 taken along th orientation of FIG. 2.

.FIG. 4 is aperspective sectional view of the container shown in FIG. 3.

FIG. 5 is a plan view of a transverse section taken along line 5-5 in FIG. 3 of the container.

FIG. 6 is a plan view comprising a transverse section taken along line 6-6 in FIG. 3.

FIG. 7 shows the electrical circuit for the motors, clutch, and controls shown in FIGS. 1 and 2.

10 and jacket 11 are supported on a hot plate-12 in FIG. 1 which contains an adjustable thermostat which can be set to provide a constant temperature. Container 10 includes a lower section 14 (defined by stepped partition 31) which houses a paddle 15 carried on a shaft 16 which extends through a vertical central tube 17. Shaft 16 is secured to chuck 18 of variable speed A.C. motor 19 which can be adjusted by variable transformer 48 to maintain a set speed. Container 10 is separated into sections 29, 30 by partitions 20 and 21 as shown by FIGS. 3, 4 and 5. A pair of hypodermic type of syringes 25, 26 shown in FIGS. 1 and 2 for ejecting drops of solution into sections 29, 30 separately are mounted with their orifices 27, 28 respectively above the openings 92, 93 respectively at the top of sections 29, 30 of container 10. The syringe 25 contains silver nitrate solution and the syringe 26 contains potassium halide solution (such as potassium bromide), which are preferably in such concentrations that when a drop of each falls simultaneously into the container 10 the two drops will produce a desired molar concentration of silver halide. This is accomplished by providing a stoicheometric ratio of concentrations of those chemicals to combine in the chemical reaction required to produce the desired silver halide emulsion. The solutions may be reversed betweenthe syringes as desired.

The plungers of the syringes 25, 26 are secured to a member 37 slidable' on member 38 (FIG. 2) secured to base 39 to which the syringes are secured in fixed position by being affixed to cradle support 40. Member 37 is also adapted to operate sensitive electrical snap action switches 41, 42 at opposite ends of its excursion. A threaded (20 pitch screw providing 0.050 inch travel/rev.) bolt 43 passes through and engages with the thread of a threaded bore through member 37 in order to provide a drive for member 37 and the plungers of syringes 25, 26. Universal coupling 44 connects bolt 43 to the output of 25:1 gear reducer box 45 which is connected at its input to the output of an electric slip clutch 46 which is connected at its input to a variable speed 228/rpm max D.C. electric motor 47.

Referring to FIGS. 1, 2, and 7, a voltage regulator 50 (FIGS. 1 and 7) is adapted to be connected to the A.C. power input 51 (FIG. 7). Regulator 50 supplies power to D.C. motor speed control 52 which is connected to drive the D.C. motor 47 to cause ejection of drops from the syringes 25, 26. Control 52 includesa reversing switch 54 for providing reversal of the motor 47. An A.C. to D.C. converter 53 (FIGS. 1 and 7) is provided to power the clutch 46 when the appropriate switches are closed. When the member 37 is up" it opens switch 42 so that the clutch 46 is disconnected. When the reversing switch 54 is operated to reverse the direction of the motor 47 and normally open bypass switch 55 is operated manually, the clutch 46 will be operated to permit motor 47 to lower member 37. As soon as switch 42 closes after member 37 has moved down slightly, manual operation of switch 55 can be discontinued and the bolt 43 will turn until member 37 opens limit switch 41. Upon subsequent reversal of switch 54 and operation of the other manual bypass switch 56, the member 37 may be raised again.

In actual operation of the equipment to produce photographic emulsion, first, the container 10 is filled with gelatin to a certain level such as that shown in FIG. 1. The gelatin is then preheated to 45-50 C (must be above 34 C gelling temperature). The motor 19 turns the paddle l5 sufficiently rapidly to create turbulence in the bottom chamber 14 of the container and additional turbulence in sections 29, 30 of the container 10 through openings 22 (FIGS. 3-5) which communicate between sections 29, 30 and chamber 14. Preferably the paddle speed is slow at the beginning and is raised to a speed which is within a range above the speed generating turbulence which does not cause excessive frothing due to turbulence. As explained above, equal volumes of the solutions in the two syringes 25, 26 are ejected at an equal rate into sections 29, 30 of container 10, respectively. The time required for ejecting of the solution contained in syringes 25, 26 is adjustable to fixed values by varying the speed control 52 for the purpose of presetting its dial toa selected position and leaving it there. In addition, the stroke of the member 37 can be adjusted by moving switches 41, 42.

All materials in contact with the chemicals including container 10 and syringes 25, 26 should be composed of inert materials and may be fabricated from glass or plexiglass but must not contain any metals which would react with the constituents of the emulsion.

The advantage of this system is that the grain size of the resulting photographic emulsion is very uniform and that very small particles may be made. In addition the process is reproducible in the sense that it produces such yields repeatedly and consistently. The mean particle size for one setting of the apparatus was 350A with a standard deviation of 13A and a mean deviation of lOA for a mean deviation expressed as a percentage of less'than three percent as compared with many times that deviation heretofore.

After mixing, the emulsion is poured into a cool environment to retard growth of crystals.

In FIG. 3, the differences in levels 90, 91 shown are due to hydrostatic pressure differences generated while paddle 15 is in operation, which reflect the slight lack of symmetry in the container 10. The stepped configuration of member 31 is provided for convenience of fabrication of the overall structure.

What is claimed is:

1. Apparatus for mixing materials including:

a first chamber for containing fluid,

said first chamber including a stirring means for generating mixing and turbulence in a fluid contained in said first chamber, drive means for turning said stirring means in said first chamber, a plurality of other chamber immediately adjacent to said first chamber for containing fluid including substantial means for communicating of fluid in said other chambers with fluid in said first chamber including direct, free, reciprocal communication of turbulence of fluid in said first chamber to said other chambers in the absence of any other means for providing circulation of fluid in said apparatus, said stirring means generating mixing and turbulence of fluid in said other chambers to a substantial degree as a result of the mixing and turbulence of fluid in said first chamber, means for adding comparable quantities of a corresponding one of different chemical solutions to each of said other chambers at a constant rate.

2. Apparatus for mixing materials including:

a first chamber for containing fluid,

said first chamber including a stirring means for generating mixing and turbulence in a fluid contained in said first chamber, drive means for turning said stirring means in said first chamber, a plurality of other chambers for containing fluid including means for communicating of fluid in said other chambers with fluid in said first chamber, said stir-' ring means generating mixing and turbulence of fluid in said other chambers as a result of the mixing and turbulence of fluid in said first chamber,

means for adding comparable'quantities of a corresponding one of different chemical solutions to each of said other chambers at a constant rate,

said means for adding comprises a slide driven at constant velocity, and means for ejecting fluids as a function of said constant velocity.

3. Apparatus in accordance with claim 1 including a jacket around said chamber containing fluid heated to a substantially constant temperature.

4. Apparatus in accordance with claim 1 wherein said drive means is operable at a velocity adjustable at will.

5. Apparatus for mixing materials including a drive, a cylinder with a mixing chamber at its base, a rotatably mounted paddle driven by said drive rotating within said mixing chamber, a pair of input chambers above said mixing chamber in said cylinder, said input chambers each communicating directly and reciprocally with said mixing chamber with turbulence in said mixing chamber generating substantial turbulence in said input chambers in the absence of any other means for providing circulation of fluid in said apparatus and means for introducing a separate chemical solution to each of said input chambers at a steady rate.

6. A method of mixing constituents of a photographic emulsion including: a

a. mixing a medium in a lower space by providing turbulence,

b. adding and mixing a first solution with a first separate quantity of said medium by coupling of said turbulence into a first separate space above said lower space,

0. simultaneously with step (b) adding and mixing a second solution with a second separate quantity of said medium by coupling of said turbulence into a second separate space above said lower space, and

d. mixing the products of steps (b) and (c) together simultaneously with steps (a,b) and (c) in said lower space through said turbulence.

7. A method of mixing materials including:

employing a container having a first chamber containing a fluid, and a plurality of other chambers for containing fluid including means for communicating of fluid in said other chambers directly and reciprocally with fluid in said first chamber and using a stirring means for generating mixing and turbulence in the fluid contained in said first chamber with communicating fluid generating mixing and turbulence in said other chambers as a result of the turbulence of fluid in said first chamber in the absense of any other means for providing circulation of fluid in said container,

and adding comparable quantities of a corresponding one of different chemical solutions to each of said other chambers at a constant rate.

8. A method in accordance with claim 7 wherein the velocity of said paddle is adjustable at will.

9. Apparatus for mixing constituents of a high resolution silver halide emulsion including: an upright cylinder including first, second, and third chambers for containing a gelatinous fluid medium,

said first chamber including a paddle for generating mixing and turbulence in said fluid contained in said first chamber, said paddle being rotatably mounted therein,

a second and third chamber above said first chamber including means for communicating of fluid in said second and third chambers with fluid in said first chamber, said paddle being driven by a motor adjustable for turning said paddle at a speed producing turbulence in said fluid without producing froth,

the lower ends of said second and third chambers including openings communicating with said first chamber,

said paddle generating mixing and turbulence of fluid in said second and third chambers as a result of the mixing and turbulence of fluid in said first chamber,

the upper ends of said second and third chambers comprising inputs, and

a slide driven at constant velocity and means for ejecting fluids as a function of said constant velocity for introducing a chemical solution to each of said input chambers at a steady rate,

said means for ejecting including syringes,

said chemical solutions comprising potassium halide in a first of said means for ejecting and silver nitrate in a second of said means for ejecting,

a jacket around said chamber containing fluid heated to a substantially constant temperature, and

said drive means being operable at a velocity adjustable at will.

10. Apparatus for mixing constituents of a high resolution photographic emulsion including: an upright cylinder including first, second, and third chambers for containing a gelatinous fluid medium,

said first chamber including a paddle for generating mixing and turbulence in said fluid contained in said first chamber, said paddle being rotatably mounted therein,

a second and third chamber each directly above said first chamber including means for communicating of fluid in each of said second and third chambers directly and reciprocally with fluid in said first chamber, said paddle being driven by a motor adjustable for turning said paddle at a speed producing turbulence in said fluid without producing froth,

the lower ends of said second and third chambers including openings communicating with said first chamber,

said paddle generating substantial mixing and turbulence of fluid in said second and third chambers as a result of the mixing and turbulence of fluid in said first chamber in the absence of any other means for providing circulation of fluid in said apparatus the upper ends of said second and third chambers comprising inputs, and

a slide driven at a substantially constant velocity and means for ejecting fluids as a function of said constant velocity for introducing a chemical solution to each'of said input chambers at a steady rate,

said means for ejecting including syringes, and

said drive means being operable at a velocity adjustable at will. 

1. Apparatus for mixing materials including: a first chamber for containing fluid, said first chamber including a stirring means for generating mixing and turbulence in a fluid contained in said first chamber, drive means for turning said stirring means in said first chamber, a plurality of other chamber immediately adjacent to said first chamber for containing fluid including substantial means for communicating of fluid in said other chambers with fluid in said first chamber including direct, free, reciprocal communication of turbulence of fluid in said first chamber to said other chambers in the absence of any other means for providing circulation of fluid in said apparatus, said stirring means generating mixing and turbulence of fluid in said other chambers to a substantial degree as a result of the mixing and turbulence of fluid in said first chamber, means for adding comparable quantities of a corresponding one of different chemical solutions to each of said other chambers at a constant rate.
 2. Apparatus for mixing materials including: a first chamber for containing fluid, said first chamber including a stirring means for generating mixing and turbulence in a fluid contained in said first chamber, drive means for turning said stirring means in said first chamber, a plurality of other chambers for containing fluid including means for communicating of fluid in said other chambers with fluid in said first chamber, said stirring means generating mixing and turbulence of fluid in said other chambers as a result of the mixing and turbulence of fluid in said first chamber, means for adding comparable quantities of a corresponding one of different chemical solutions to each of said other chambers at a constant rate, said means for adding comprises a slide driven at constant velocity, and means for ejecting fluids as a function of said constant velocity.
 3. Apparatus in accordance with claim 1 including a jacket around said cHamber containing fluid heated to a substantially constant temperature.
 4. Apparatus in accordance with claim 1 wherein said drive means is operable at a velocity adjustable at will.
 5. Apparatus for mixing materials including a drive, a cylinder with a mixing chamber at its base, a rotatably mounted paddle driven by said drive rotating within said mixing chamber, a pair of input chambers above said mixing chamber in said cylinder, said input chambers each communicating directly and reciprocally with said mixing chamber with turbulence in said mixing chamber generating substantial turbulence in said input chambers in the absence of any other means for providing circulation of fluid in said apparatus and means for introducing a separate chemical solution to each of said input chambers at a steady rate.
 6. A method of mixing constituents of a photographic emulsion including: a. mixing a medium in a lower space by providing turbulence, b. adding and mixing a first solution with a first separate quantity of said medium by coupling of said turbulence into a first separate space above said lower space, c. simultaneously with step (b) adding and mixing a second solution with a second separate quantity of said medium by coupling of said turbulence into a second separate space above said lower space, and d. mixing the products of steps (b) and (c) together simultaneously with steps (a,b) and (c) in said lower space through said turbulence.
 7. A method of mixing materials including: employing a container having a first chamber containing a fluid, and a plurality of other chambers for containing fluid including means for communicating of fluid in said other chambers directly and reciprocally with fluid in said first chamber and using a stirring means for generating mixing and turbulence in the fluid contained in said first chamber with communicating fluid generating mixing and turbulence in said other chambers as a result of the turbulence of fluid in said first chamber in the absense of any other means for providing circulation of fluid in said container, and adding comparable quantities of a corresponding one of different chemical solutions to each of said other chambers at a constant rate.
 8. A method in accordance with claim 7 wherein the velocity of said paddle is adjustable at will.
 9. Apparatus for mixing constituents of a high resolution silver halide emulsion including: an upright cylinder including first, second, and third chambers for containing a gelatinous fluid medium, said first chamber including a paddle for generating mixing and turbulence in said fluid contained in said first chamber, said paddle being rotatably mounted therein, a second and third chamber above said first chamber including means for communicating of fluid in said second and third chambers with fluid in said first chamber, said paddle being driven by a motor adjustable for turning said paddle at a speed producing turbulence in said fluid without producing froth, the lower ends of said second and third chambers including openings communicating with said first chamber, said paddle generating mixing and turbulence of fluid in said second and third chambers as a result of the mixing and turbulence of fluid in said first chamber, the upper ends of said second and third chambers comprising inputs, and a slide driven at constant velocity and means for ejecting fluids as a function of said constant velocity for introducing a chemical solution to each of said input chambers at a steady rate, said means for ejecting including syringes, said chemical solutions comprising potassium halide in a first of said means for ejecting and silver nitrate in a second of said means for ejecting, a jacket around said chamber containing fluid heated to a substantially constant temperature, and said drive means being operable at a velocity adjustable at will.
 10. Apparatus for mixing constituents of a High resolution photographic emulsion including: an upright cylinder including first, second, and third chambers for containing a gelatinous fluid medium, said first chamber including a paddle for generating mixing and turbulence in said fluid contained in said first chamber, said paddle being rotatably mounted therein, a second and third chamber each directly above said first chamber including means for communicating of fluid in each of said second and third chambers directly and reciprocally with fluid in said first chamber, said paddle being driven by a motor adjustable for turning said paddle at a speed producing turbulence in said fluid without producing froth, the lower ends of said second and third chambers including openings communicating with said first chamber, said paddle generating substantial mixing and turbulence of fluid in said second and third chambers as a result of the mixing and turbulence of fluid in said first chamber in the absence of any other means for providing circulation of fluid in said apparatus the upper ends of said second and third chambers comprising inputs, and a slide driven at a substantially constant velocity and means for ejecting fluids as a function of said constant velocity for introducing a chemical solution to each of said input chambers at a steady rate, said means for ejecting including syringes, and said drive means being operable at a velocity adjustable at will. 